Fifth wheel trailers and tow vehicles for fifth wheel trailers are generally well known in the art. Fifth wheel trailers are much longer, roomier, and heavier than typical tent campers and travel trailers, and thus a fifth wheel trailer typically requires a specially modified, relatively heavy tow vehicle such as a heavy duty pickup truck. The front portion of a fifth wheel trailer extends over the rear portion of the tow vehicle so that a portion of the trailer's weight can be carried over the rear axle of the tow vehicle. In order to accommodate the weight of the trailer a special hitch assembly is generally required.
One apparatus for allowing a pickup truck, even a short bed truck, to pull a fifth wheel trailer is to use a sliding hitch assembly as described in U.S. Pat. No. 6,308,977 ('977 patent). The '977 patent describes a sliding hitch assembly with two main parts, a base assembly and a hitch assembly. The hitch assembly attaches to the hitch pin of a trailer; the base assembly is mounted in the bed of a vehicle. The hitch assembly is slidably mounted on the base assembly and operates by mechanically sliding the hitch pin rearward from the cab as the trailer pivots relative to the vehicle. By sliding the hitch rearward, the distance between the hitch pin and the cab increases during turns, thereby allowing turns up to 90 degrees without the trailer contacting the cab. To allow rotation to occur between the hitch assembly and base assembly a capture plate is used to hold the hitch assembly in fixed rotational alignment with the trailer.
In the '977 patent, the sliding hitch assembly includes a capture plate which is fastened to the underside of the pin box and which mates with a cutout in the hitch pin slot of the hitch assembly, thereby restricting rotation between the hitch assembly and the pin box. The capture plate of the '977 patent is a flat piece of metal which is sized to mate with the cutout of the hitch pin slot of the sliding hitch assembly. Traditionally, the plate is either fastened directly to the pin box—such as with bolts or screws drilled into the pin box—or by welding or otherwise mounting brackets to the pin box, with the capture plate then mounted to those brackets.
Other prior art capture plates are constructed from a flat plate with a wedge extending from the bottom side. The wedge is shaped in a Y-shape and is sized to fill the pin slot on the hitch assembly, thereby preventing rotation between the capture plate and the hitch assembly. The top side of the capture plate has a lip which extends around the entire perimeter of the plate, with screws which mount through the lip and into or against the pin box, thereby preventing rotation between the capture plate and the pin box.
The previous approaches to capture plate design have some drawbacks. First, each requires modification to the pin box. Second, the traditional method of restricting rotation between the capture plate and the hitch assembly may form too strong of a connection between the trailer and the hitch assembly such that when rotational forces between the trailer and truck become excessive, costly failure can occur in the trailer, the vehicle, or the hitch. Third, pin box size can vary from trailer to trailer and thus the previous capture plate designs require customized mounting hardware for pin boxes of different dimensions.
Accordingly, there exists a need for a capture plate which can be removably mounted to a fifth wheel trailer's pin box without modifying the pin box. There also exists a need to design a capture plate which will preferentially fail so that the trailer, vehicle and hitch assembly are protected from damage when subjected to excessive stress. There further exists a need to design a capture plate which is readily and inexpensively adjustable to accommodate variously sized pin boxes.